[ARM] Remove EPXA10DB machine support

EPXA10DB seems to be uncared for:
- the "PLD" code has never been merged
- no one has reported that this platform has been broken since
  at least 2.6.10
- interest seems to have dried up around March 2003.

Therefore, remove EPXA10DB support.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>